The objective of this research progrram is to develop a simple cannulae circulatory support system (both left and right ventricles) for patients with temporary cardiac failure unresponsive to conventional therapy. In the first nine months of this grant, surgical techniques, blood access, and cannulae fabrication methods were refined. Left ventricular right atrial, pulmonary artery, and aortic cannulae, with removable balloon obturators, were implanted in seven anticoagulated, instrumented sheep, for control nonpumping hemodynamic and blood chemistry studies, partial transapical left ventricular bypass (Qr equals less than over qt 0.5) was studied in eleven instrumented sheep for up to ten days of pumping. The trend in these sheep with normal hearts was a gradual increase in cardiac output during prolonged partial bypass pumping. Free plasma hemoglobin and platelet count minimally changed with one week of partial LV bypass. Studies in Year Two of this grant will include partial and total LV bypass, right ventricular bypass, and the effects of pulsatile and nonpulsatile aortic return.